1. Field of the Invention
A motor housing assembly of the type for enclosing a blower motor in an automotive heating and air conditioning (HVAC) system.
2. Description of the Prior Art
The electric motor used to power the fan in the HVAC system is typically retained in a motor housing assembly that is mounted to the HVAC housing. These motors produce disagreeable levels of noise such as the tick-click noise generated by the travel of the brushes of the motor over the separation gaps in the commutator at low rotational speeds. Such noise can also be generated by debris in the motor or imperfections in the thrust bearings or excessive clearance between the shaft and the bearings of the motor. Various techniques have been employed to isolate the vibrations and noise generated by the motor from the adjoining structure. For example, it has been known to use elastomeric grommets that surround the fasteners used to secure the motor housing assembly to the air case. It has also been known to make the motor housing assembly from a resilient, vibration-damping material. In addition, a hush panel attached to the underside of the instrument panel absorbs or masks such noise. In some cases, a separate motor cover with a foam lining covers the motor. Examples of the prior art housings are disclosed in U.S. Pat. No. 5,786,647 to Vollmer et al.; U.S. Pat. No. 5,905,320 to Periyathamby et al.; U.S. Pat. No. 6,262,504 to Bartlett; U.S. Pat. No. 6,448,678 to Simpson and U.S. Pat. No. 6,717,299 to Bacile et al.
When the motor housing assembly is made from more rigid materials, such as plastics, it has also been known to wrap or otherwise surround the circumference of the motor with a resilient band or shroud intended to isolate the motor from the motor housing assembly. When the motor is received in the motor housing assembly, the vibrations and noise generated by the motor are dampened by the band or shroud and are not transmitted radially outwardly to the HVAC housing. Other motor housing assemblies incorporate one or more damping pads located between an end of the motor and the motor housing.